After Gastric Bypass Surgery, Insulin Goes Down Before Weight Loss has Time to Happen

In “Obesity Is Always and Everywhere an Insulin Phenomenon” I argue that insulin levels are a crucial determinant of weight gain and weight loss. I follow up on this idea in further posts,

and apply this idea in

Today, let me point your attention toward an important study that gives more evidence of insulin’s importance for weight loss. In “Loss of Insulin Resistance after Roux-en-Y Gastric Bypass Surgery: a Time Course Study,” Kusal Wickremesekera, Geoff Miller, Tissa DeSilva Naotunne, Graham Knowles and Richard S Stubbs write:

Gastric bypass has repeatedly been shown to improve and even cure type 2 diabetes by substantially improving insulin resistance. … The changes in insulin resistance seen after gastric bypass, which are responsible for the resolution or improvement of type 2 diabetes occur within 6 days of the surgery, before any appreciable weight loss has occurred. 

Insulin resistance is when many cells in the body have become somewhat “deaf” to insulin; the insulin-producing cells then respond by “shouting”: producing more insulin. Because not all responses to insulin are equally tamped down, the extra insulin increases the incidence of insulin side-effect. Even though it is produced by one’s own body, insulin must be considered a drug, and high doses cause trouble.

This link and those above will take you to the full abstract. Unfortunately, the article itself is behind a paywall, but going through the University of Colorado Boulder’s library website allows me free access. I consider the following paragraph the centerpiece of the paper. In order to understand it, you need to know the definition of “humoral”: relating to the body fluids.

There is abundant evidence from many centers indicating that type 2 diabetes can be cured by gastric bypass and by other forms of bariatric surgery. That this is achieved before appreciable loss of weight is an important clue to improving our under-standing of insulin resistance. Whereas obesity is conventionally thought to produce insulin resistance, it may emerge that obesity is another manifestation of insulin resistance. Put simply, insulin resistance may cause obesity, not vice versa. It has been postulated that gastric bypass improves diabetes through influences on the entero-insular axis, through a humoral effect. Our understanding of the changes in insulin resistance following surgery has been assisted by the documentation of marked falls in plasma insulin levels within days of gastric bypass.

Let me unpack this. It says that surgeries in the general category to which stomach stapling belongs can cure type 2 diabetes. Type 2 diabetes is basically a bad case of insulin resistance in which key cells have become so deaf to insulin that even if a lot of insulin is produced, they aren’t responding to the insulin enough. This is a bad situation!

The authors say explicitly that insulin resistance may cause obesity, as opposed to obesity causing insulin resistance.

What causes insulin resistance? High levels of insulin.

How can insulin resistance be reduced? Low levels of insulin.

How can insulin levels be reduced? One drastic way to lower insulin levels is gastric bypass surgery. It isn’t fully understood how gastric bypass surgery does this. Another way to reduce insulin levels and hence lower insulin resistance is to fast—that is, to eat nothing for a while. This effect is big enough that the authors worry in the paper about the reduced insulin resistance comes from the fact that people can’t eat for a while after gastric bypass surgery. Fasting is something you can do at home without having to go to the hospital!

Somewhat strangely, the authors write as if having some kind of operation is the only thing that would ever lead individuals to fast:

Without a sham operation being performed on severely obese individuals, it will be hard to resolve the role of fasting on insulin resistance in these patients. However, sham operations can be performed on animals, and experiments in a non-obese diabetic rat model support the hypothesis that the loss of insulin resistance is related to surgical bypass of components of the gut.

But many people are trying out fasting as a way to improve their insulin resistance.

I think of fasting (drinking water—and tea or coffee if desired—but not eating) as the most important idea I have come across for weight loss. It also has other health benefits. And if you are eating food that tends to produce relatively little insulin (see Forget Calorie Counting; It's the Insulin Index, Stupid), my experience and that of others I know is that fasting will be surprisingly easy. Or to put things another way, fasting gets a bad rap because people think of the agony of fasting in the wake of eating sugary food and other food that ramps up insulin. (Another factor in a low-insulin-index diet making it easier to fast may be that a low-insulin-index diet tends to be high in healthy fats, which makes the transition to burning one’s own body fat easier.)

A good place to start in putting these ideas into practice is last week’s post: “3 Achievable Resolutions for Weight Loss.” If you try these ideas, please let me know if they work for you—and even more importantly if they don’t work for you. I want to understand what works in practice, and hearing about things that didn’t work is a key way to get there.

Don’t miss my other posts on diet and health:

I. The Basics

II. Sugar as a Slow Poison

III. Anti-Cancer Eating

IV. Eating Tips

V. Calories In/Calories Out

VI. Wonkish

VIII. Debates about Particular Foods and about Exercise

IX. Gary Taubes

X. Twitter Discussions

XI. On My Interest in Diet and Health

See the last section of "Five Books That Have Changed My Life" and the podcast "Miles Kimball Explains to Tracy Alloway and Joe Weisenthal Why Losing Weight Is Like Defeating Inflation." If you want to know how I got interested in diet and health and fighting obesity and a little more about my own experience with weight gain and weight loss, see “Diana Kimball: Listening Creates Possibilities” and my post "A Barycentric Autobiography.